The family of human retroviruses has four members: HIV-1, HIV-2, HTLV-I, and HTLV-II. Large scale screening assays do not yet exist for HIV-2 and HTLV-1 antibodies. To achieve this, we will construct prokaryotic expression vectors to produce recombinant env, gag and accessory-gene proteins. The resulting recombinant proteins will be purified and used to screen HIV-2 and HTLV-I antibodies. This data will also allow for the evaluation of the necessity of including accessary gene product in the screening assay and the possibility of using accessory gene product to distinguish HIV-2 from HIV-1 infection. Confirmatory assays, such as radioimmunoprecipitation, virus isolation, immunoblotting, and polymerase chain reaction, will be employed to verify ELISA reactivity. This research could lead to the development of testing algorithms for HIV-2 and HTLV-1. The proposed study will be conducted in four phases. Phase one involves the construction of expression vectors, and the purification of recombinant proteins. Phase two consists of formatting ELISA procedures and evaluating confirmatory assays. A panel of well-defined serum reagents, which includes serum samples from known HIV-2 or HTLV-1 infected people will serve as positive controls, and serum samples from uninfected people and patients with autoimmune diseases will serve as negative controls. Phase three involves testing stored serum and lymphocyte diseases will serve as negative controls. Phase three involves testing stored serum and lymphocyte samples collected from epidemiological studies of a West African population at risk for HIV-2 infection and a Japanese population at risk for HTLV-I infection. This phase of the study will help to determine which assays are useful in distinguishing HIV-2 from HIV-1 and whether HIV-2 and to determine which assays are useful in distinguishing HIV-2 from HIV-1 and whether HIV-2 ad HTLV-I accessory genes should be included in their respective screening assays. Phase four involves testing 40,000 samples collected over a one year period from a northeastern United States blood center. The possibility of conducting a similar study for HIV-2 will be discussed at a future time with our long-time West African collaborators and will not be in the scope of this proposal.